"Richard Riley" wrote in message
...
A friend of mine has just had a Continental 550 destroy itself. He's
asked for my advice, but all my experience is with Lycomings. If
anyone has experience with 550's and can comment, I'd be thankful.

The #3 cyl has the piston crown pretty much gone, along with the
rings. The other pistons show significant crown damage as well. The
local A&P believes it's detonation.

The engine has about 60 hours since new. My friend was the pilot for
the last 4 hours or so. As he's been flying it he's been getting much
higher fuel burn than he expected - cruise lean was 18-20 GPH. He's
also seen higher oil temps than expected - 220-240.

The mags were unchanged from their original factory timing, but it
turns out they were set at 18 and 20 degrees.

Any ideas here? He was running it at no more than 25" and 2500 RPM.
I'd have thought all that fuel would have kept it cool.

http://www.avweb.com/news/columns/182132-1.html
Pelican's Perch #43:
Detonation Myths